I have several questions

1. How to make respawn for func_breakable? Like, when player destroyed func_breakable, this enity respawns in some seconds
2. My map using +use buttons, how to do so, that on my map, command "tf_allow_player_use 1" don't need to be written in console?
3. Why i can't see the water after complie?

1. You'll probably need an env_entity_maker and a point_template to make it respawn. Although it might be worth looking into entity_spawn_manager / entity_spawn_point instead, particularly if you want it to spawn in a semi-random location.

For reference, Valve uses entity_spawn_manager to respawn the pumpkin bombs on its Halloween maps.